Grim global warming outlook for India post 2030: IISc's research

BANGALORE: J Srinivasan, professor at the Indian Institute of Science (IISc) in Bangalore, goes through his work days secretly hoping for a global major climate crisis. As a leading climate change scientist in India, he knows that the country and the world are inching towards disaster. A serious crisis now would shake up people and make them act, he thinks. "I remember the ozone hole crisis while I was a student," says Srinivasan. "Scientists were talking about it for a long time, but they took action only when the hole appeared over the pole."

Srinivasan has reasons to worry, particularly for India. Some of his colleagues at the IISc have done the first multi-model study of climate change for India for the rest of the century. It makes grim reading, particularly after the year 2030. If the world does not cut down its carbon dioxide quickly, temperatures will rise - compared to pre-industrial times - over the Indian subcontinent by 1.7 to 2 degree centigrade by 2030, and 3.3 to 4.8 degree centigrade by 2080.

Since we have warmed by slightly less than a degree so far, the next 20 years would see an additional warming of nearly 1 degree centigrade. Says Govindaswamy Bala, professor at the Divecha Centre for Climate Change at the IISc: "This is the first multi-model study anyone has done over the Indian sub-continent, and it has shown agreement over historical data."

This study is to be published soon by the journal Current Science. Bala and his colleagues have used the new climate models that are going to be used for the next report of the Intergovernmental Panel for Climate Change (IPCC). They were available around May this year, and the IISc team has been quick to use them to give the first forecasts. All other studies have looked at only one model, and there are large variations between predictions of different models. The average of different models, as done by the current study, shows good agreement with what has happened in the past. So it is considered a more reliable indicator of future climate trends than those predicted by individual models.

The temperature increase has serious consequences for the Indian sub-continent. Water is expected to become scarce, forests to decline and agriculture output to fall. All models forecast an increase in rainfall over the century, but no one can predict how this increase will happen. What would happen if the increase is over the sea, concomitant with a decrease over land? Models also predict increase in rainfall to happen in intense bursts and not spread over a long period. All this would point to a water scarcity over the sub-continent, although the precise amount will depend on how the rainfall is distributed over the country.

In the Current Science study, rainfall - if we do nothing about reducing carbon dioxide - would increase 4 to 5 per cent by 2030 and 6 per cent to 14 per cent by the end of the century. Also shown to increase is the frequency of extreme precipitation. "We have very little ability to predict rainfall accurately," says Srinivasan. For example, in the last decade, the end of September has been a dry period. This is not in tune with what happened over the last century. No one knows why this happens.

Increase in temperature has serious repercussions on our forestry. A study last year by the Centre for Sustainable Technologies at IISc found that nearly 40 per cent of India's forests are at risk. This includes one-third of Western Ghats and almost 50 per cent of Himalayan forests. This team is now working on the new models to estimate the impact of temperature rise on forests. In normal circumstances, plant species migrate and replace vanishing species. But with roads and fields interspersing forests, this is not easy. Says NH Ravindranath, professor at the Centre for Sustainable Technologies: "It will take hundreds of years for forests and biodiversity to grow back again."

So, what could shake up the world? Severe weather is certainly the one to look for and one such phenomenon could be the drought over the American Mid-West. In March this year, temperatures were 15 degrees higher than normal there. The US Mid-West is far away from the sea and so does not get rainfall copiously, as moisture-laden winds have to travel long distances. This area is thus sensitive to climate changes. Yet this area is the bread-basket of the world. Severe and successive droughts there could reduce US farm production enough for policymakers to start thinking seriously, like when the ozone hole problem happened. So should we pray for a calamity to save the world?